The present invention generally relates to nonwoven materials with a voluminous z direction component which have a surface skin added on either one or both sides of the nonwoven.
There are a number of products in various industries, including automotive, office and home furnishings, construction, and others; that require materials having a z-direction thickness to provide thermal, sound insulation, aesthetic, and other performance features. In many of these applications it is also required that the material be thermoformable to a specified shape and rigidity. In the automotive industry these products often are used for shielding applications such as noise and thermal barriers in automotive hood liners and firewall barriers. These automotive materials may or may not have an aesthetic cover material incorporated into the part, which can also protect the core from abrasion, etc. In home and office furnishing, and construction applications these materials are often used as structural elements to which exterior decorative materials might be added.
Additionally, these and other industries require that the materials deliver these properties in a cost effective manner. Often the barrier properties are best accomplished by using specialty fibers and or materials that generate a high level of performance, but also introduce significant cost to the substrate. Especially in a voluminous thickness substrate, the introduction of even a small percent of these materials into the shield material can introduce a significant level of cost to the overall substrate. For this reason composites having specialty surface layers are often used to provide these barrier properties. An example would be a thin layer of high cost but highly effective specialty material laminated to a voluminous lower cost core material. While the resulting composite costs less than more homogenous composites, there are disadvantages such as the need for additional processing steps and the potential delamination of the skin layer.
The present invention is an alternative to the prior art. It is a non-woven material with different functional zones to provide various desired properties of the material localized to the vertically oriented zones where required. Low melt fibers that can be used to construct a “skin” on one, or both, planar sides of the non-woven material can be localized to the sides of the material specifically. The formation of this skin can provide a barrier between the atmosphere and the interior of the non-woven material, can provide a smoother more aesthetically pleasing surface, and can improve other performance features such as abrasion, sound absorption, and rigidity. In the case of a heat shield, the material can become oxygen-starved, due to the lower air permeability of the material skin and facilitate its flame resistance. The invention has superior molding performance because the low melt fibers can be not only optimized in quantity for superior performance, but can also be localized to optimize performance for specific mold design. Superior acoustic properties are achieved by creating a distinct skin on the non-woven with lower air permeability than the core. By using low melt fibers of the same chemical nature as the voluminous core, an essentially single recyclable material can be achieved. All of these benefits are achieved at competitive costs and weight compared to the existing products.